Conventionally, the mobile communication system is known where the result of measurement of reception quality state in a downlink channel is reported as a CQI from a communication terminal apparatus such as a mobile phone to a base station, to perform link adaptation for a downlink channel (for example, transmission power control, adaptive modulation, and adaptive demodulation) or scheduling of packets to transmit to each user (for example, see Patent Literature 1). Here, although a CQI is equivalent to Ec/I0 of the common pilot channel (ratio of received chip energy to interference power), according to the present application, a CQI is not limited to Ec/I0, and also refers to an indicator or feedback information that show the reception quality state of radio channel such as propagation loss, reception power, and the ratio of signal to interference power.
Further, conventionally, because frequency-selective fading occurs following the trend of broadbandization in a mobile communication system, a mobile communication system for efficiently transmitting data is known where each of a plurality of users use a different frequency band having a good condition. According to this mobile communication system, the whole frequency band to use is divided into a plurality of sub-bands, and a CQI is measured and reported per sub-band.
Further, in recent years, in the digital radio communication system, high speed transmission has started gaining popularity. Further, in the future mobile communication system, further broadbandization is expected to realize high transmission rate, short delay, and large capacity.